Cstone PharmaceuticalsHKEX: 2616

CStone Announces Publication of GEMSTONE-303 Study Results for Sugemalimab in JAMA

· Issued by CStone Pharmaceuticals

Suzhou, China - CStone Pharmaceuticals ('CStone', HKEX: 2616), an innovation-driven biopharmaceutical company focused on the research and development of anti-cancer therapies, today announced the publication of the GEMSTONE-303 study results for sugemalimab (brand name: Cejemly) in the prestigious Journal of the American Medical Association (JAMA).

GEMSTONE-303 is a Phase 3, randomized, double-blind, placebo-controlled study designed to evaluate the efficacy of sugemalimab in combination with capecitabine and oxaliplatin (CAPOX) compared to placebo plus CAPOX as first-line treatment for patients with unresectable locally advanced or metastatic G/GEJ adenocarcinoma with PD-L1 CPS =5. The dual primary endpoints were OS and investigator-assessed PFS. Key secondary endpoints included PFS assessed by the Blinded Independent Central Review Committee (BICR), objective response rate (ORR), and duration of response (DoR).

The GEMSTONE-303 article published in JAMA highlights the following key efficacy and safety findings: In patients with PD-L1 CPS =5, the sugemalimab group showed statistically significant and clinically meaningful improvements in both OS and PFS compared with the control group.

Median OS was 15.6 months in the sugemalimab group compared with 12.6 months in the control group, with a hazard ratio (HR) of 0.75 (95% CI, 0.61-0.92), P=0.006, indicating that sugemalimab plus CAPOX could reduce the risk of death by 25%.

Median PFS was 7.6 months in the sugemalimab group versus 6.1 months in the control group, with a HR of 0.66 (95% CI, 0.54-0.81), P

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